Continuous supply fluid reservoir

ABSTRACT

An assembly for holding a fluid includes an auxiliary reservoir inside a main reservoir. The auxiliary reservoir includes an auxiliary reservoir shell with a fill passage at or near its bottom. The auxiliary reservoir shell also has a vent passage at or near its top. The fill passage and the vent passage fluidically connect the auxiliary reservoir to the main reservoir. A fluid inlet is located inside the main reservoir and outside of the auxiliary reservoir. A fluid outlet located inside the auxiliary reservoir between the fill passage and the vent passage.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/233,332, now U.S. Pat. No. 8,181,746, entitled “Continuous SupplyFluid Reservoir,” filed on Sep. 18, 2008 by Szolomayer, et al.

BACKGROUND

The present invention relates to reservoirs, and more particularly, tofluid reservoirs for use in gas turbine engines.

In many gas turbine engines, a fluid reservoir is used to store liquidlubricating oil for engine components. A supply pump attached to asupply passage takes liquid from the fluid reservoir to the enginecomponents, and a scavenge pump attached to a scavenge passage returnsthe liquid from the engine components to the fluid reservoir. When ascavenge pump returns liquid to the fluid reservoir, it typicallyreturns air along with the liquid. Consequentially, the fluid reservoirholds air and liquid. During normal operating conditions, the liquidsettles at the bottom of the fluid reservoir and displaces air to thetop. However, a fluid reservoir for a gas turbine engine mounted on anaircraft may experience “negative gravity” conditions such as theaircraft turning upside down, the aircraft accelerating toward the Earthat a rate equal to or greater than the rate of gravity, or the aircraftdecelerating at the end of a vertical ascent. Under negative gravityconditions, the liquid in the fluid reservoir can rise to the top, whichcan expose the opening of the supply passage to air and interrupt thesupply of liquid to the engine components. Certain engine components,such as gears and bearings, can be damaged in a relatively short periodof time without lubrication.

Typically, a lubrication system includes a single fluid reservoir and asingle supply pump driven by a high pressure spool. When the highpressure spool stops rotating or rotates at a reduced rpm (revolutionsper minute), the single supply pump will ordinarily provide little or noliquid to engine components. Certain engine components can continuerotating when the high pressure spool stops rotating or rotates at areduced rpm (revolutions per minute). For example, while the aircraft isparked on the ground or during an in-flight engine shutdown, wind mayrotate a fan, a low pressure compressor, and, consequently, the lowpressure spool and the corresponding gears and bearings. Certain gearsand bearings could be damaged by non-lubricated operation.

SUMMARY

According to the present invention, an assembly for holding a fluidincludes an auxiliary reservoir inside a main reservoir. The auxiliaryreservoir includes an auxiliary reservoir shell with a fill passage ator near its bottom. The auxiliary reservoir shell also has a ventpassage at or near its top. The fill passage and the vent passagefluidically connect the auxiliary reservoir to the main reservoir. Afluid inlet is located inside the main reservoir and outside of theauxiliary reservoir. A fluid outlet is located inside the auxiliaryreservoir between the fill passage and the vent passage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a lubrication apparatus of the presentinvention.

FIG. 2A is a schematic sectional view of a fluid storage assembly of thepresent invention.

FIG. 2B is a schematic sectional view of an alternative embodiment ofthe fluid storage assembly of FIG. 2A.

FIG. 2C is a schematic sectional view of another alternative embodimentof the fluid storage assembly of FIG. 2A.

FIG. 3A is a schematic sectional view of an open roll-over valve for analternative embodiment of the auxiliary reservoir of FIG. 2A.

FIG. 3B is a schematic sectional view of a closed roll-over valve forthe alternative embodiment of the auxiliary reservoir of FIG. 3A.

FIG. 3C is a schematic sectional view of an open roll-over valve foranother alternative embodiment of the auxiliary reservoir of FIG. 2A.

FIG. 4A is a schematic sectional view of an open roll-over valve foranother alternative embodiment of the auxiliary reservoir and thedeaerator of FIG. 2A.

FIG. 4B is a schematic sectional view of a closed roll-over valve forthe alternative embodiment of the auxiliary reservoir and the deaeratorof FIG. 4A.

FIG. 4C is a schematic sectional view of an open roll-over valve foranother alternative embodiment of the auxiliary reservoir and thedeaerator of FIG. 2A.

DETAILED DESCRIPTION

In general, the present invention provides a lubricating system having amain reservoir and an auxiliary reservoir inside and at a bottom of themain reservoir. Liquid in the main reservoir flows into the auxiliaryreservoir so that the auxiliary reservoir is substantially full ofliquid during normal operating conditions. The size and location ofpassages between the auxiliary reservoir and the main reservoir areconfigured so that the auxiliary reservoir remains substantially full ofliquid, as opposed to allowing the liquid to quickly flow back into themain reservoir, during brief periods of negative gravity conditions. Aroll-over valve can further reduce liquid flow through one or morepassages during negative gravity conditions. This allows a supplypassage connected to the auxiliary reservoir to have a relativelycontinuous supply of liquid for lubricating components on a gas turbineengine.

FIG. 1 is a schematic view of lubrication apparatus 10, which isconfigured for storing lubricating oil for use in a gas turbine engine(not shown), for supplying lubricant to various engine components, andfor scavenging lubricant from the same. In the illustrated embodiment,the system generally acts on two fluids: air and liquid lubricating oil.Lubrication apparatus 10 includes fluid storage assembly 12, breather14, main pump assembly 16, main pump shaft 18, main supply stage 20,main scavenge stages 22A, 22B, and 22C, auxiliary pump assembly 24,auxiliary pump shaft 26, auxiliary supply stage 28, auxiliary scavengestage 30, engine components 32A, 32B, 32C, and 32D, main supply passage34, supply sub-passages 36A, 36B, 36C, and 36D, auxiliary supply passage38, scavenge passage 40, scavenge sub-passages 42A, 42B, 42C, and 42D,combined main scavenge passage 44, backup connection passage 46, checkvalves 48A and 48B, deoiler 50, filter 52, and auxiliary scavengepassage 54.

Fluid storage assembly 12 stores two fluids, liquid L and air A, in amanner described further below. Main pump assembly 16 includes mainsupply stage 20 and main scavenge stages 22A, 22B, and 22C. Main supplystage 20 and main scavenge stages 22A, 22B, and 22C are all driven bymain pump shaft 18, which can be connected through gearing to a highpressure spool (not shown) of a gas turbine engine. Main supply stage 20pumps liquid L from fluid storage assembly 12 through main supplypassage 34. Main supply passage 34 splits downstream of main supplystage 20 into supply sub-passages 36A, 36B, 36C, and 36D. Supplysub-passages 36A, 36B, 36C, and 36D deliver liquid L to enginecomponents 32A, 32B, 32C, and 32D, respectively. Main scavenge stages22A, 22B, and 22C pump liquid L and air A from engine components 32A,32B, and 32C through scavenge sub-passages 42A, 42B, and 42C,respectively. Scavenge sub-passages 42A, 42B, and 42C combine intocombined main scavenge passage 44 downstream of main scavenge stages22A, 22B and 22C. Liquid L is pumped through combined main scavengepassage 44, through check valve 48B, through filter 52, through scavengepassage 40, and into fluid storage assembly 12. Filter 52 reduces debrisflow into fluid storage assembly 12. Check valve 48B allows fluid flowfrom main scavenge stages 22A, 22B and 22C to filter 52 but impedesfluid flow in an opposite direction.

Auxiliary pump assembly 24 includes auxiliary supply stage 28 andauxiliary scavenge stage 30. Auxiliary supply stage 28 and auxiliaryscavenge stage 30 are both driven by auxiliary pump shaft 26, which canbe connected through gearing to a low pressure spool (not shown).Auxiliary supply stage 28 pumps liquid L from fluid storage assembly 12through auxiliary supply passage 38 to engine component 32D. Undernormal operation, auxiliary supply passage 38 and main supply passage 34both supply liquid L to engine component 32D. Auxiliary scavenge stage30 pumps liquid L and air A from engine component 32D, through scavengesub-passage 42D, through auxiliary scavenge passage 54, to filter 52. Atfilter 52, liquid L and air A from auxiliary scavenge passage 54 combinewith liquid L and air A from combined main scavenge passage 44 to flowthrough scavenge passage 40 into fluid storage assembly 12.

Backup connection passage 46 connects auxiliary supply passage 38 tomain supply passage 34, at points downstream of auxiliary supply stage28 and main supply stage 20. In the illustrated embodiment, check valve48A allows fluid flow from auxiliary supply passage 38 through backupconnection passage 46 to main supply passage 34 but impedes fluid flowin an opposite direction. If pressure in main supply passage 34 isgreater than pressure in auxiliary supply passage 38, check valve 48Areduces fluid flow through backup connection passage 46. Under theseconditions most or all of liquid L pumped by auxiliary supply stage 28can be routed to engine component 32D. If, on the other hand, pressurein main supply passage 34 is less than pressure in auxiliary supplypassage 38, check valve 48A allows fluid flow through backup connectionpassage 46. Under these conditions, a portion of liquid L pumped byauxiliary supply stage 28 can be routed to engine component 32D andanother portion of liquid L pumped by auxiliary supply stage 28 can berouted to engine components 32A, 32B, and 32C.

In an alternative embodiment, check valve 48A can be replaced with anorifice. Liquid L can then flow through backup connection passage 46 ineither direction according to a pressure gradient. In either embodiment,auxiliary supply stage 28 can act as a backup pump to some or all enginecomponents when fluid flow through main supply passage 34 is reduced orstopped.

In one embodiment, engine component 32D can be a fan drive gear systemto operably connect a fan to a low pressure spool (one example of a fandrive gear system is described in U.S. patent application Ser. No.11/906,602 entitled EPICYCLE GEAR TRAIN FOR VARIABLE CYCLE ENGINE). Thefan drive gear system can have journal bearings that benefit fromuninterrupted lubrication. A gear ratio for the fan drive gear systemcan allow the fan to rotate at a speed slower than the low pressurespool. In another alternative embodiment, engine component 32D can be afront bearing compartment. The front bearing compartment can support alow pressure compressor. In yet another alternative embodiment, enginecomponent 32D can be a combination of the fan drive gear system and thefront bearing compartment. Engine component 32C can be a middle bearingcompartment for bearings that support the low pressure compressor and/ora high pressure compressor. The middle bearing compartment can alsoinclude an auxiliary gearbox. Engine component 32B can be a rear bearingcompartment for bearings that support a high pressure turbine and/or alow pressure turbine. Engine component 32A can be an extra bearingcompartment for bearings that support the low pressure turbine. Inalternative embodiments, engine components 32A, 32B, 32C, and 32D can beany set of components in a piece of machinery that use the same liquid.

When the gas turbine engine is not operating, wind can blow through androtate the fan (not shown). The fan's rotation can rotate the fan drivegear system which rotates the low pressure spool, which activatesauxiliary pump assembly 24. Wind can also rotate the high pressurecompressor attached to the high pressure spool, but it may not rotatefast enough to effectively activate main pump assembly 16. In such asituation, auxiliary supply stage 28 can supply enough liquid L toengine components 32A, 32B, 32C, and 32D to reduce engine component wearfrom wind-induced movement. One or more engine components 32A, 32B, 32C,and 32D can have ball bearings able to operate with little or nolubrication for a period of time but that nonetheless benefit fromlubrication.

FIG. 2A is a schematic sectional view of fluid storage assembly 12 thatincludes main reservoir 60, main reservoir shell 62, main reservoir topportion 64, scavenge inlet 66, scavenge flow 68—which is a mixture ofliquid L and air A, main supply orifice 70, main supply screen 72,deaerator center portion 74, deaerator spiral 76, spiral fluid outlet78, breather outlet 80, breather flow 82, auxiliary reservoir 84,auxiliary reservoir bottom 86, auxiliary reservoir shell 88, auxiliaryshell top 90A, auxiliary shell bottom 90B, vent holes 92, fill holes 94,auxiliary supply orifice 96, auxiliary supply screen 98, and reservoirinterface 100.

In the illustrated embodiment, main reservoir 60 has a generallycylindrical main reservoir shell 62 that encloses a cavity for holdingliquid L and air A. Auxiliary reservoir 84 has a generally conicalauxiliary reservoir shell 88 and a dome-shaped auxiliary reservoirbottom 86. Auxiliary reservoir 84 is located generally inside mainreservoir 60, attached near the bottom of main reservoir 60 at reservoirinterface 100. Auxiliary reservoir shell 88 has vent holes 92 nearauxiliary shell top 90A and fill holes 94 near auxiliary shell bottom90B. In the illustrated embodiment, vent holes 92 are circular holesthrough auxiliary reservoir shell 88. Fill holes 94 can also be circularholes through auxiliary reservoir shell 88, and can have flow areaslarger than the flow areas of vent holes 92. In alternative embodiments,vent holes 92 can be any passage that allows air flow from auxiliaryreservoir 84 to main reservoir 60, and fill holes 94 can be any passagethat allows liquid flow from main reservoir 60 to auxiliary reservoir84. Furthermore, in alternative embodiments, auxiliary reservoir shell88 can be any shape that tapers from auxiliary shell bottom 90B toauxiliary shell top 90A, such as a dome.

Deaerator 58 is located inside main reservoir 60, attached to mainreservoir top portion 64. Deaerator 58 includes deaerator center portion74, which has a generally frusto-conical shape and an air-permeablesurface. Deaerator spiral 76 wraps around deaerator center portion 74with scavenge inlet 66 at its top and spiral fluid outlet 78 at itsbottom. Scavenge passage 40 attaches to main reservoir 60 at scavengeinlet 66. Scavenge flow 68 indicates the direction of liquid L and air Aflow from scavenge passage 40 (not shown in FIG. 2A), through scavengeinlet 66, and into deaerator 58. Under normal operation, gravity directsliquid L down deaerator spiral 76 and through spiral fluid outlet 78 toa main cavity of main reservoir 60. Air A is generally directed throughthe permeable surface of deaerator center portion 74 and throughbreather outlet 80. Breather flow 82 indicates the direction of air Aflow out of breather outlet 80 to deoiler 50 and breather 14 (shown inFIG. 1). Deoiler 50 removes fine particles of liquid L from air A anddirects liquid L back to fluid storage assembly 12 and air A to breather14. In alternative embodiments, deaerator 58 can be nearly any deaeratorconfigured to separate air A from liquid L.

Main supply passage 34 extends into main reservoir 60, adjacent to mainreservoir shell 62. Main supply passage 34 can be a cylindrical pipewith main supply orifice 70 opening into main reservoir 60. Main supplyscreen 72 covers main supply orifice 70 to prevent debris in mainreservoir 60 from entering main supply passage 34. Liquid L is pumpedout of main reservoir 60 through main supply passage 34 by main supplystage 20 as described above with respect to FIG. 1.

Auxiliary supply passage 38 extends into auxiliary reservoir 84.Auxiliary supply passage 38 is a generally vertically oriented,substantially cylindrical pipe with auxiliary supply orifice 96 openinginto auxiliary reservoir 84. Under normal, upright operating conditionsas in the illustrated embodiment, auxiliary supply orifice 96 is locatedvertically higher than fill holes 94 and vertically lower than ventholes 92. Thus, auxiliary supply orifice 96 is generally between each offill holes 94 and each of vent holes 92 even when fluid storageapparatus 12 is oriented sideways or upside-down. Auxiliary supplyscreen 98 covers auxiliary supply orifice 96 to prevent debris inauxiliary reservoir 84 from entering auxiliary supply passage 38. LiquidL is pumped out of auxiliary reservoir 84 through auxiliary supplypassage 38 by auxiliary supply stage 28 as described above with respectto FIG. 1.

Under normal operating conditions, fluid storage assembly 12 can beorientated generally upright, with deaerator 58 located above auxiliaryreservoir 84, as illustrated. Liquid L can settle at the bottom of mainreservoir 60 and auxiliary reservoir 84 by way of gravity. A liquidlevel within main reservoir 60 can be high enough to cover main supplyorifice 70, auxiliary supply orifice 96, and all of auxiliary reservoirshell 88. Liquid L can exit main reservoir 60 through main supplypassage 34 and exit auxiliary reservoir 84 through auxiliary supplypassage 38. Liquid L exiting auxiliary reservoir 84 can be replaced byliquid L from main reservoir 60 flowing through fill holes 94. A smallamount of liquid L from main reservoir 60 can also flow through ventholes 92 but the primary function of vent holes 92 is to vent air, asfurther explained below. In this manner, auxiliary reservoir 84 canremain substantially full of liquid L.

Under certain conditions, liquid L may not necessarily settle at thebottom of main reservoir 60. This could occur under commonly occurringphysical conditions such as fluid storage assembly 12 inverting, fluidstorage assembly 12 accelerating toward the Earth at a rate equal to therate of gravity (zero gravity) or greater than the rate of gravity(negative gravity), or fluid storage assembly 12 decelerating at the endof a vertical ascent. For convenience, these conditions, and otherconditions creating a similar effect, are collectively referred toherein as “negative gravity” conditions. Under negative gravityconditions, liquid L can settle at the top of main reservoir 60 whileair A settles at the bottom of main reservoir 60. Main supply orifice 70can then be temporarily exposed to air A. If vent holes 92 aresufficiently small and if auxiliary reservoir 84 is substantially fullof liquid L immediately prior to the onset of negative gravityconditions, auxiliary reservoir 84 will remain substantially full ofliquid L immediately after the onset of negative gravity conditions.Auxiliary supply orifice 96 can then remain submerged in liquid L sothat auxiliary supply passage 38 can have an uninterrupted supply ofliquid L for a period of time during negative gravity conditions. Asliquid L exits auxiliary reservoir 84 through auxiliary supply orifice96 and/or through vent holes 92, air A can enter auxiliary reservoir 84through fill holes 94. When negative gravity conditions end and normaloperating conditions resume, liquid L can once again settle at thebottom of fluid storage assembly 12. Any air A that entered auxiliaryreservoir 84 can exit to main reservoir 60 through vent holes 92,replaced by liquid L entering through fill holes 94. Auxiliary reservoir84 can then return to a state of being substantially full of liquid L.If a sufficiently small quantity of air A entered auxiliary reservoir 84during negative gravity conditions, auxiliary supply orifice 96 can havean uninterrupted supply of liquid L during normal operating conditions,negative gravity conditions, and the transitions therebetween.

In alternative embodiments, such as that shown in FIG. 2B, main supplypassage 34, main supply orifice 70, and main supply screen 72 can belocated inside auxiliary reservoir 84 along with auxiliary supplypassage 38. Thus, main supply orifice 70 and auxiliary supply orifice 84can both benefit from uninterrupted supply of liquid L during normaloperating conditions, negative gravity conditions, and the transitionstherebetween.

In further alternative embodiments, such as that shown in FIG. 2C, mainsupply passage 34, main supply orifice 70, and main supply screen 72 canbe omitted in favor of having a single auxiliary supply passage 38,auxiliary supply orifice 96, and auxiliary supply screen 98 located inauxiliary reservoir 84. Auxiliary supply passage 38 can branch to supplyliquid L to both main supply stage 20 and auxiliary supply stage 28.

As described above, the flow of liquid L from auxiliary reservoir 84 tomain reservoir 60 during negative gravity conditions is limited by therelatively small flow area of vent holes 92. In alternative embodiments,a roll-over valve can be used to limit such flow. FIGS. 3A and 3B areschematic sectional views of roll-over valve 102 for an alternativeembodiment of auxiliary reservoir 84′. In FIG. 3A, roll-over valve 102includes auxiliary reservoir disc 104, auxiliary reservoir disc edge106, support stems 108, support stem top ends 110, support stem bottomends 112, sleeve 114, sleeve top 116, and sleeve bottom 118. Auxiliaryreservoir disc 104 is a circular sheet of metal, having a concave shapewith auxiliary reservoir disc edge 106 at a perimeter thereof. Auxiliaryreservoir disc 104 has a diameter generally larger than a diameter ofvent hole 92′. The concave side of auxiliary reservoir disc 104 attachesto four support stems 108 at support stem top ends 110 (only two supportstems 108 are shown in FIG. 3A). Support stems 108 can be cylindricalbeams, each with an axis parallel to an axis of the portion of auxiliarysupply passage 38′ that extends inside auxiliary reservoir 84′. Supportstems 108 are each aligned adjacent to auxiliary supply passage 38′.Sleeve 114 can be a cylindrical pipe, partially enclosing and sharing anaxis with auxiliary supply passage 38′. Sleeve 114 is spaced apart fromauxiliary supply passage 38′ by a distance greater than the diameter ofsupport stems 108. Sleeve 114 has a solid sleeve bottom 118. Sleevebottom 118 is a flat bottom that attaches sleeve 114 to auxiliary supplypassage 38′. Sleeve 114 is open at sleeve top 116. Support stems 108pass through sleeve top 116 so as to slide freely between sleeve 114 andsupply passage 38′. Support stems 108 are spaced apart from each otherso as to allow liquid L to flow into auxiliary supply orifice 96′.

Auxiliary reservoir 84′ is the same shape in FIG. 3A as in FIG. 2Aexcept that auxiliary shell top 90A′ has been cut off, causing auxiliaryreservoir shell 88′ to have a substantially frusto-conical shape.Consequently, there is one relatively large vent hole 92′ in FIG. 3A, asopposed to several relatively small vent holes 92 as in FIG. 2A. Whensupport stem bottom ends 112 are substantially adjacent to sleeve bottom118, auxiliary reservoir disc 104 is spaced substantially apart fromvent hole 92′. Roll-over valve 102 is then in an “open” position. LiquidL can flow through both auxiliary supply orifice 96′ and vent hole 92′.Under normal operating conditions, roll-over valve 102 is held open bygravity.

FIG. 3B is a schematic sectional view of roll-over valve 102 in a“closed” position. In the closed position, support stem bottom ends 112are spaced apart from sleeve bottom 118, and auxiliary reservoir discedge 106 is substantially adjacent to auxiliary reservoir shell 88′. Thelocation of auxiliary reservoir disc edge 106 substantially adjacent toauxiliary reservoir shell 88′ reduces the flow of liquid L through venthole 92′. Liquid L can continue to flow through auxiliary supply orifice96′. Under negative gravity conditions, roll-over valve 102 can beclosed. In alternative embodiments, roll-over valve 102 can be nearlyany valve that allows the flow of air A through vent hole 92′ undernormal operating conditions but reduces the flow of liquid L throughvent hole 92′ under negative gravity conditions.

FIG. 3C is a schematic sectional view of an alternative embodiment ofroll-over valve 102 in an “open” position. In the embodiment illustratedin FIG. 3C, support stem 108′ is a one piece perforated cylinder asopposed to four separate support stems 108 as illustrated in FIGS. 3Aand 3B. Support stem 108′ can reduce weight and complexity while stillallowing fluidic travel to supply orifice 96′. Aside from the differencein support stem 108′, roll-over valve 102 is essentially the same inFIG. 3C as in FIGS. 3A and 3B.

FIGS. 4A and 4B are schematic sectional views of roll-over double valve120 for an alternative embodiment of auxiliary reservoir 84′ anddeaerator 58′. In FIG. 4A, roll-over double valve 120 includes auxiliaryreservoir disc 104, auxiliary reservoir disc edge 106, deaerator disc122, deaerator disc edge 124, connecting stem 126, connecting stemstopper 127, connecting stem top end 128, connecting stem bottom end130, side support beams 132, side support beams inner ends 134, sidesupport beams outer ends 136, and slider 138. Auxiliary reservoir disc104 is a circular sheet of metal, concave with auxiliary reservoir discedge 106 at a perimeter. Auxiliary reservoir disc 104 has a diameterlarger than a diameter of vent hole 92′. Deaerator disc 122 is also acircular sheet of metal, having a concave shape with deaerator disc edge124 at a perimeter. Deaerator disc 122 has a diameter larger than adiameter of deaerator vent passage 140. Connecting stem 126 is acylindrical beam, with an axis parallel to an axis of the portion ofauxiliary supply passage 38′ (not shown in FIGS. 4A and 4B) that extendsinside auxiliary reservoir 84′. Connecting stem top end 128 is attachedto a center of the concave side of deaerator disc 122, and connectingstem bottom end 130 is attached to a center of the convex side ofauxiliary reservoir disc 104. Slider 138 is a cylindrical ring with ahollow center with a diameter greater than the diameter of connectingstem 126. Connecting stem 126 shares an axis with and slides freelyinside of slider 138. Connecting stem stopper 127 is rigidly attached toconnecting stem 126 with a width larger than an inner diameter of slider138. Connecting stem stopper 127 limits the distance connecting stem 126can slide through slider 138 in one direction. While in the “open”position, connecting stem stopper 127 rests on an upper surface ofslider 138. Side support beams 132 are cylindrical beams that attach toslider 138 at side support beam inner ends 134 and attach to mainreservoir shell 62′ at side support beam outer ends 136. When auxiliaryreservoir disc 104 is spaced from vent hole 92′, air A can flow throughvent hole 92′. When deaerator disc 122 is spaced from deaerator ventpassage 140, air A can flow through deaerator vent passage 140. Undernormal operating conditions, roll-over double valve 120 is held “open”by gravity in this manner.

FIG. 4B is a schematic sectional view of roll-over double valve 120 in a“closed” position. In the closed position, auxiliary reservoir disc edge106 is substantially adjacent to auxiliary reservoir shell 88, anddeaerator disc 122 is substantially adjacent to deaerator vent passage140. Connecting stem 126 is configured to have a length sufficient toallow auxiliary reservoir disc edge 106 to be substantially adjacent toauxiliary reservoir shell 88′ and deaerator disc 122 to be substantiallyadjacent to deaerator vent passage 140 at the same time. Roll-overdouble valve 120 limits the flow of liquid L through both vent hole 92′and deaerator vent passage 140 in the closed position. Under negativegravity conditions, roll-over double valve 120 can be closed. Inalternative embodiments, roll-over double valve 120 can be nearly anyvalve that allows the flow of air A through vent hole 92′ and deaeratorvent passage 140 under normal conditions but reduces the flow of liquidL through vent hole 92′ and deaerator vent passage 140 under negativegravity conditions.

FIG. 4C is a schematic sectional view of an alternative embodiment ofroll-over double valve 120 in an “open” position. In the embodimentillustrated in FIG. 4C, perforated cone 142 can attach between auxiliaryreservoir shell 88′ and slider 138. Perforated cone 142 providesstructural support for slider 138 while still allowing fluid flowthrough vent hole 92′. Consequently, side support beams 132 can beomitted to save weight and reduce complexity.

It will be recognized that the present invention provides numerousbenefits and advantages. For example, the present invention can providelubrication to components with improved reliability, as described above.Moreover, a system having a single fluid storage assembly with tworeservoirs according to the present invention can weigh less than asystem having two separate fluid storage assemblies. Furthermore, byallowing liquid returned from various engine components to intermix in asingle fluid storage assembly, heat can be dissipated from a warmercomponent to a cooler component. Still furthermore, the illustrated tworeservoir configuration allows for improved deaeration of the liquid atthe time of entering the auxiliary reservoir because the extended paththe fluid must take to enter the auxiliary reservoir allows moreopportunity for any air bubbles to liberate.

Although the present invention has been described with reference topreferred embodiments, workers skilled in the art will recognize thatchanges may be made in form and detail without departing from the spiritand scope of the invention. For example, the shape of main reservoirshell 62, auxiliary reservoir bottom 86, and auxiliary reservoir shell88 can be varied as necessary for particular applications. The number ofpumps, number of liquid delivery locations, number of vent passages, andnumber of roll-over valves can also vary. Additionally, the use of fluidstorage assembly 12 as described in FIGS. 2A, 2B, 2C, 3A, 3B, 4A, and 4Bis not limited to its use in lubrication apparatus 10 as described inFIG. 1. Instead, fluid storage assembly 12 can be used with virtuallyany aircraft engine. Moreover, fluid storage assembly 12 can be used tohold fluid in any apparatus that benefits from any of the advantages offluid storage assembly 12.

What is claimed is:
 1. An assembly comprising: a main reservoir forholding a fluid; an auxiliary reservoir located inside the mainreservoir near a bottom of the main reservoir, the auxiliary reservoircomprising: an auxiliary reservoir shell comprising a shell top and ashell bottom; at least one fill passage through the auxiliary reservoirshell at or near the shell bottom; and at least one vent passage throughthe auxiliary reservoir shell at or near the shell top, wherein theauxiliary reservoir is fluidically connected to the main reservoir bythe fill passage and the vent passage; a fluid inlet located inside themain reservoir and outside of the auxiliary reservoir; and a fluidoutlet located inside the auxiliary reservoir and vertically positionedbetween the fill passage and the vent passage.
 2. The assembly of claim1, wherein the vent passage has a smaller flow area than the fillpassage.
 3. The assembly of claim 1, wherein the fill passage isconfigured to allow fluid flow from the main reservoir to the auxiliaryreservoir under normal operating conditions.
 4. The assembly of claim 1,wherein the vent passage is configured to allow air flow from theauxiliary reservoir to the main reservoir under normal operatingconditions.
 5. The assembly of claim 1, and further comprising: a firstsupply passage in fluid communication with the fluid outlet; and a firstpump operably connected to the first supply passage for pumping thefluid from the auxiliary reservoir to a first engine component.
 6. Theassembly of claim 5, and further comprising: a second supply passageconnected to the main reservoir; and a second pump operably connected tothe second supply passage for pumping the fluid from the main reservoirto a second engine component.
 7. The assembly of claim 6, and furthercomprising: a backup connection passage fluidically connected to thefirst supply passage at a first interface between the first pump and thefirst engine component to the second supply passage at a secondinterface between the second pump and the second engine component. 8.The assembly of claim 5, wherein the first engine component comprises afan drive gear system for a gas turbine engine, wherein the fan drivegear system operably connects a fan to a low pressure spool.
 9. Theassembly of claim 1, wherein the auxiliary reservoir shell is rigid andtapers from the shell bottom to the shell top.
 10. An assemblycomprising: a main reservoir for holding a fluid; an auxiliary reservoirlocated inside the main reservoir near a bottom of the main reservoir,the auxiliary reservoir comprising: an auxiliary reservoir shellcomprising a shell top and a shell bottom; a fill passage through theauxiliary reservoir shell at or near the shell bottom; and a ventpassage through the auxiliary reservoir shell at or near the shell top,wherein the auxiliary reservoir is fluidically connected to the mainreservoir by the fill passage and the vent passage; a fluid inletlocated inside the main reservoir and outside of the auxiliaryreservoir; a fluid outlet located inside the auxiliary reservoir andvertically positioned between the fill passage and the vent passage; anda valve configured to allow fluid flow through the vent passage in afirst valve position and to reduce fluid flow through the vent passagein a second valve position.
 11. The assembly of claim 10, wherein thevalve is in the first valve position under normal operating conditionsand in the second valve position under negative gravity conditions. 12.The assembly of claim 10, and further comprising: a deaerator comprisinga deaerator vent passage for allowing air flow between the deaerator andthe main reservoir, and wherein the valve is further configured to allowfluid flow through the deaerator vent passage in a first valve positionand to reduce fluid flow through the deaerator vent passage in a secondvalve position.